This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A104108 #11 Oct 13 2019 10:18:32
%S A104108 1,0,0,0,1,0,0,1,1,1,0,0,0,1,1,1,0,1,1,0,0,0,1,0,1,1,1,0,1,1,0,0,0,1,
%T A104108 1,1,0,0,0,1,0,0,1,1,1,0,0,0,1,1,1,0,1,1,0,0,0,1,1,1,0,0,0,1,0,0,1,1,
%U A104108 1,0,1,0,0,0,1,0,0,1,1,1,0,0,0,1,1,1,0,1,1,0,0,0,1,0,0,1,1,1,0,1,1,0,0,0,1
%N A104108 a(1) = 1, c(1)=1, if A(k) = sequence of first c(k) terms and if B(k) is A(k) with 0's and 1's exchanged, then A(k+1) = A(k)B(k) and c(k+1)= 2*c(k) if a(k) = 1, A(k+1) = A(k),0,B(k) and c(k+1)= 2*c(k)+1 if a(k) = 0.
%t A104108 f[l_]:=Join[l,If[l[[Floor[Log[2,Length[l]]]+1]]==1,{},{0}],1-l];Nest[f,{1},7] (* _Ray Chandler_, Apr 05 2009 *)
%Y A104108 Cf. A104104, A104105, A104106, A104107.
%K A104108 easy,nonn
%O A104108 1,1
%A A104108 _Leroy Quet_, Mar 04 2005
%E A104108 Edited and extended by _Ray Chandler_, Apr 05 2009